基于Weibull分布函数的花椒真空干燥动力学特性

摘要

The goal of this study is going to shorten the drying time,improve the quality and reduce the energy consumption of Chinese prickly ash for its vacuum drying.Weibull distribution was adopted to analysis the drying kinetics characteristics of Chinese prickly ash for its Scale parameter α,Shape parameterβ,Moisture effective diffusion coefficients Deff and Geometric factor Rgunder the varied drying conditions of vacuum (0.02,0.04,0.06 MPa) and temperatures(50,60,70℃).And the quality of dried product was investigated by Weight Grade Method.The result showed that there is a positive correlation between drying time and vacuum(V) and drying temperatures(T);The value ofβ ranged between 1.336 9 and 1.613 2,the values are closed to 1 and that means the drying curves obeys the exponential distribution.The values of Deff are 0.715 × 10-s-2.244 × 10-8m2/s,and the value of Rg under varied drying conditions are closed to 1,and that means the model of Deff have a good fitness.The average value of Ea is 24.36 kJ/mol.Besides,the color of the product was significant affected by drying temperature,and there was a positive correction between breakage rate and vacuum,drying temperature.%为了缩短花椒真空干燥时间,提高其干制品品质,降低能耗,选取真空度V(0.02、0.04、0.06MPa)和干燥温度T(50、60、70℃)进行全面试验.对花椒尺度参数α、形状参数β、有效扩散系数Deff及几何参数Rg进行研究,利用Weibull分布函数对数据进行拟合,计算花椒真空干燥平均干燥活化能Ea,通过加权评分法对各干燥条件下干制品品质进行综合评价.研究表明,干燥温度(T)和真空度(V)与干燥时间均呈正相关性;花椒形状参数β值为1.3369～1.613 2,接近于1,即干燥特性曲线严格服从指数分布;有效水分扩散系数Deff值为0.715×10-8-2.244×10-8m2/s,不同干燥条件下,几何参数Rg值均接近于1,即估算有效系数Dcal与试验所得有效扩散系数Deff非常接近,有效水分扩散系数线性拟合方程拟合度较高.对花椒真空干燥活化能Ea求解,其值为24.36 kJ/mol,易于干燥;花椒色泽受温度影响较大,温度越低所得△E*值越小,即色泽变化越小,破壳率μ与干燥温度和真空度均呈正相关性.